1. Field of the Invention
The present invention relates to a method for designing a ring network, and particularly a method for efficiently accommodating paths of various client signals to a ring network in consideration of an arrangement order on the ring network of a route for accommodating client signal paths.
2. Description of the Related Art
Recently, an optical transmission/reception apparatus (generically called ADM on λ, ADM on a card, etc.), which has an Add/Drop function of a SONET signal and a SDH signal (simply “SONET/SDH” hereinafter) together with an optical signal transponder function (i.e., the function of generating a signal light), has been developed. A SONET signal is based on ANSI T1. 105 recommendation: Synchronous Optical Network Basic Description Including Multiplex Structures, Rates and Formats, and an SDH signal is based on ITU-T Recommendation G. 803: Architecture of Transport Networks Based on the Synchronous Digital Hierarchy).
The above mentioned optical transmission/reception apparatus enables a construction of an upper layer network accommodating diverse client signals including a SONET signal, SDH signal (simply “SONET/SDH” hereinafter), Ethernet (registered trademark) and fiber channel, on an optical network structured by a wavelength division multiplexing (WDM) system.
Embodiment of the present invention relates to a technological design for accommodating a client signal preferable to an SONET/SDH ring network constructed by using the above transponder apparatus. More particularly, the embodiment relates to SONET BLSR (Bidirectional Line Switched Ring), or SDH Multiplex Section Shared Protection Ring network. The SONET BLSR network will be explained as an example of a typical ring network.
Conventionally, when a ring network is designed on an optical network structured like a mesh network, each time one SONET BLSR network is designed, a ring route on the optical network is designed and the accommodation of a client signal to the ring route is performed. In this case, on the SONET BLSR ring, the arrangement order of a route for accommodating the client signal is taken into consideration so as to prevent the overlap of a communication route between terminal nodes as transmitting and receiving terminals of the client signal, thereby accommodating the client signal more efficiently. However, a sequential relationship between the routes for accommodating the client signal is not conventionally considered and this becomes one factor for reducing the accommodation efficiency.
Japanese Unexamined Patent Application Publication No. 2000-232472 discloses a technology for automatically designing a transmission route on a ring network. Further, PCT Japanese Translation Patent Publication No. 2003-520496 discloses a technology for designing the accommodation of a client signal.
Conventionally, on the ring networks, such as SONET BLSR ring, the arrangement order on the ring network of a communication route between terminal nodes as transmitting and receiving terminals of a client signal is not appropriately taken into consideration. This is one of the factors for obstructing accommodation efficiency of the client signal.